Currently available video display technologies allow full-screen display of a plurality of video streams on a single TV display, monitor or even a cinema screen, to allow the plurality of users to watch different streams simultaneously.
For example, this can be achieved by time-interleaving the successive frames of the video streams. First, a first frame of stream “A” can be displayed, then a first frame of stream “B”, then a first frame of stream “C”, and next a second frame of stream “A”, a second frame of stream “B” and so on. So-called shutter glasses can be used by individual users (watchers) to watch particular video streams, as known from the 3D video technology. The shutter glasses have lenses which change from transparent to opaque and vice versa. The process of changing the state of the lenses is controlled electronically and is relatively fast comparing to human perception. The glasses are synchronized with the display such that when the frames of the stream “A” are displayed, the shutter glasses “1” are transparent and the other glasses are opaque, and when the frames of the stream “B” are displayed, the shutter glasses “2” are transparent and the other glasses are opaque, and so on. If the video streams are monoscopic, both lenses for the left and right eye change their state simultaneously. As a result, the watcher wearing the glasses “1” observes only frames related to stream “A” while the watcher wearing the glasses “2” observes only the frames of stream “B” and so on. Therefore, the video streams can be selected independently by different watchers for simultaneous watching on the same display.
The aforementioned method may be also applied for simultaneous watching of 3D video streams, as well as simultaneous watching of 3D and 2D video streams. The technology is limited mainly by the maximum amount of frames that can be displayed per a unit of time by the displaying device.
The video streams may be provided from one source or a plurality of different sources, such as a computer, a game console, a television set-top box, a DVD player, a smartphone etc. For example, a game console may provide two distinct video streams, each for a different player. Alternatively, a single display can be used by two watchers, wherein one watcher intends to watch a video stream from a game console and the second watcher intends to watch a television program from a set-top box.
Each watcher should have an individual headset to receive a sound track corresponding to the watched video stream. In another scenario of use, different watchers can watch the same video stream, but with different sound tracks (for example different languages).
There is a need to provide, for each watcher of the multi-stream display, a way to control the display of the stream watched by the watcher, for example by providing a menu that is at least partially independent for each watcher, such that each watcher may individually control the display.
To browse and operate the multi instantiations menu, for convenience, two or more RCUs are recommended, one for each watcher. Therefore, each watcher has an associated RCU. This requires to synchronize (pair) each RCU with the shutter glasses such that the device driving the display can associate the RCU with a particular watcher. The synchronized RCU-shutter glasses pair can be registered for a particular user at the image generating device, so that the image generating device knows how many watchers are currently active and therefore how many signals shall be generated.
There are known various methods for pairing (synchronization) of devices with each other. Typically, a bidirectional radio communication and dedicated pushbuttons are needed for initialization of the synchronization. For example, Wi-Fi devices use WPS (Wi-Fi Protected Setup) synchronization. It is also possible to permanently associate two devices with each other, for example the shutter glasses can be permanently paired with a particular RCU. However, such permanent pairing is inconvenient and in case one of the devices is damaged, the other device becomes useless.
There is a need to provide a convenient method for registering shutter glasses in an image generating device, which would be easy to use and involve minimum effort from the user to register the shutter glasses.